A member of the Xenohuman Terrain Team program, Dr. Mary Shelton is currently attached to 3rd Squad, 1st Platoon, 1st DOG. This makes her one of the few females posted to Third Landing. Shelton was born in 1975 and grew up in New York City, New York. She is notoriously foul-mouthed and has a tendency to talk to herself.

She holds a doctorate in cultural anthropology and was recruited to the XTT program from the US Agency for International Development (USAID). She speaks fluent Spanish, having worked in Latin America for many years.

While Shelton frequently exhibits the behavior of a stereotypical New Yorker, she can also demonstrate extraordinary patience and attention to detail when required. As she explains it, "As a grad student I sorted and cataloged pottery shards for a year. In Mexico, where it takes a month to get anything accomplished. Two if you want it fast. I wouldn't say it taught me Zen detachment, but I know wanting something to be over won't make it happen any quicker, so just accept it."

Shelton has proven effective in the field, quickly learning the basics in common xenofauna languages and is extraordinarily good at understanding the Dungeon layout, including likely positions for both the natural and created traps that infest it. This has made her a valued member of 3rd Squad, which has adopted the nickname of "The Bloody Marys." The nickname arose from an early patrol where the squad was ambushed by orcs. Many members of the squad received bullet wounds, overwhelming the medical supplies. After the orcs were defeated, Shelton produced a box of tampons from her personal supplies which were used as emergency field dressings. The additional supplies are credited with saving the life of Pvt. Mendez. Though tampons have long been used to staunch penetration wounds (http://www.snopes.com/military/tampon.asp), the members of Third Squad were taunted with the nickname "The Bloody Marys" until they defiantly adopted it as their own, including the design of a unofficial unit patch featuring the eponymous drink.

Rumors are rife in the confined and stressful environment of LONG STAIR and Shelton has attracted more than her share. Many of them are exaggerated for comic effect and are used as jokes to defuse the anxiety caused by her being a female who accompanies combat operatives. Few of these rumors are believed by the people who tell or hear them, but they serve to diffuse tension. Shelton is aware that rumors, often misogynistic ones, circulate about her but since they are never repeated to her she ignores them as part of dealing with sexism. 2nd Lt. J. Belmont, commander of 1st Platoon denounces them as unfounded and foolish whenever he overhears them but otherwise has taken no action..

She has of late been asking rhetorical questions to the Dungeon itself, though when pressed she will admit that "something" is listening to her. Shelton is a strong believer in the theory that the Dungeon is psychoreactive, changing itself in response to the thoughts and emotions of delvers and insists that the XTT program will not truly succeed until higher-level phenomenon are understood, though her rationale of "so we can figure out who is f******g with us and what the f*****s want" has not won her many allies amongst the LONG STAIR science staff.

She goes far beyond that theory in insisting that an intelligence of some kind is deliberately altering the environment in order to study human reactions. This theory is not accepted by LONG STAIR command, but she is amassing circumstantial evidence supporting her beliefs. This evidence is being collected in a Power Point presentation tentatively titled "Dungeons And Doctrines" which she intends to present to command at a future date.

Shelton is assisted in the field by Pvt. Kenneth "Shooter" Wilson, a straitlaced Southern Baptist from Paintsville, Kentucky who is uncomfortable with her frequent profanity. However his skill with a camera is equal to his prodigious skill with a rifle, leading to his current nickname and making him her most frequent assistant and bodyguard. Shelton carries a surplus .45 Colt 1911A pistol as part of her gear and is trained in its use, but has never fired it outside of the range.